GREEN INVESTMENT: John Paulson announces his gift at Bethesda Fountain’s famed Angel of the Waters sculpture in the park yesterday. Photo: Dan Brinzac

Central Park has never seen this much green.

A 56-year-old hedge-fund manager who was wheeled around Central Park as a baby yesterday pledged an extraordinary $100 million to the nonprofit that runs the 843-acre oasis in the heart of Manhattan.

John Paulson’s super-sized gift to the Central Park Conservancy is believed to be the largest ever made to a park in the United States.

“I wanted to give an amount that would have an impact on the park, and that’s how I arrived at the number I did,” Paulson said at a celebratory press conference with Mayor Bloomberg in front of the Bethesda Fountain.

A self-made billionaire who grew up in Queens and attended Bayside HS, Paulson made the killing of a lifetime in 2007 by betting that the overheated housing market would collapse. A year later, it did, in spectacular fashion. His wealth, once estimated at $15.5 billion, reportedly fell to $11.8 billion after a premature losing bet on a strong economic recovery.

But Paulson, who joined the conservancy’s board in June, has emerged as one of the city’s up-and-coming philanthropists. This was his largest charitable gift to date.

Paulson said he always intended to focus his charitable donations in New York, and quickly concluded that Central Park would top his list.

“When I was a baby, my parents strolled me around in a carriage,” he said in a low-key speech.

“When I was a teenager, I used to hang around Bethesda Terrace. When I got older, I did Rollerblading. I still run and cycle, and I come here with my children all the time. My mother was rolled around when she was a child in Central Park, and my grandparents, God bless them, had their first dates holding hands in Central Park . . . I thought to myself, Central Park is such a unique place, unlike anywhere else in the world.”

Paulson generally stays out of the news. But he made headlines last year by scolding Occupy Wall Street demonstrators who marched on his home across from Central Park at Fifth Avenue, saying those who generate jobs and tax revenues here shouldn’t be vilified, because Singapore would welcome them in a split-second.

The mayor described Paulson’s gift as “fantastic.”

“I don’t think there’s any other city, any other country in the world, where private philanthropy is as important and as available as it is here,” said Bloomberg, who is himself one of the nation’s most generous philanthropists.

Doug Blonsky, the conservancy’s president, said half of Paulson’s money would be used to beef up an endowment that now stands at $144 million.

The other half, he said, would go toward dozens of capital projects, from the renovation of playgrounds to new landscaping and irrigation for the park’s heavily used entrance at Columbus Circle.

“It really does touch every acre of the park,” said Blonsky.

“We are finally breaking the cycles of decline and [restoration] that have hit Central Park so much,” he added. “A lot of people don’t realize if you take out the 30 years of the Central Park Conservancy, the 120 years before us, the park was mostly in bad shape.”

The conservancy and private donors fund about 85 percent of the park’s $46 million annual operating cost.

Bloomberg said Paulson’s enormous cash infusion would not free up city funds for other parks.

“One has nothing to do with the other,” the mayor said. “It doesn’t mean we’re going to transfer any moneys from one place to another.”